1. treated with a secondary stain applied after an initial stain in microscopy or laboratory preparation
Usage: technical; biology/microbiology

1. past tense and past participle of counterstain; to apply a secondary stain to a specimen after an initial stain
Usage: technical; biology/microbiology

Examples

• The counterstained bacterial cells appeared red under the microscope.
• The technician counterstained the slide with methylene blue after the initial Gram stain.
• Counterstained tissue samples revealed both the primary and secondary structures.
• The pathologist counterstained the biopsy to enhance contrast between different cell types.
• Counterstained preparations are essential in many diagnostic laboratory procedures.